Javascript Canvas Game - How to know when object crosses its own path? - javascript

I am new to Javascript. I am trying to make a canvas game similar to Snake, but without the fruits.
The game is over if the player crosses his own path. The following is my code. Do you know how can I determine when the red rectangle crosses its own path and use the game over function?
Thank you!
var player;
var touch = 0;
function startGame() {
myGameArea.start();
player = new component(30, 30, "red", 270, 270);
}
var myGameArea = {
canvas: document.createElement("canvas"),
start: function() {
this.canvas.width = 600;
this.canvas.height = 600;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
window.addEventListener('keydown', function(e) {
myGameArea.key = e.keyCode;
})
},
clear: function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y) {
this.gamearea = myGameArea;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.update = function() {
ctx = myGameArea.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
this.newPos = function() {
this.x += this.speedX;
this.y += this.speedY;
}
}
function updateGameArea() {
/*myGameArea.clear();*/
player.speedX = 0;
player.speedY = 0;
if (myGameArea.key == 37) {
player.speedX = -10;
}
if (myGameArea.key == 39) {
player.speedX = 10;
}
if (myGameArea.key == 38) {
player.speedY = -10;
}
if (myGameArea.key == 40) {
player.speedY = 10;
}
if (player.x <= 0 || player.x >= 570 || player.y <= 0 || player.y >= 570) { //When the player goes out of the canvas
gameOver();
}
player.newPos();
player.update();
}
function gameOver() {
var r = confirm("GAME OVER. Restart?");
if (r == true) {
window.location.reload();
} else {
window.open("https://www.google.ca");
}
}
canvas {
padding-left: 0;
padding-right: 0;
margin-left: auto;
margin-right: auto;
display: block;
background-color: #000;
}
<body onload="startGame()">
</body>

Array as a Queue.
The way this game is traditionally done is using a special array type called a queue. Like a real queue you have items added at one end and removed at the other, or first in first out.
Javascript does not have a special array type for a queue but it has all the functions needed to implement a queue.
Push and shift
Array.push(item); // pushes an item onto the top of the array
Array.shift(); // removes an item from the start of the queue
So for the snake game imagine the head as the end of the queue. Every time it moves one forward you place another item on the queue. At the other end you remove an item if the length of the array is longer than the snake length;
var snake = [];
var snakeLength = 10;
function snakeMove(x,y){ // position to move head
checkForHit(x,y); // see below
snake.push({x:x,y:y}); // put another headpiece on the queue
if(snake.length > snakeLength){ // is the length longer than it should be
snake.shift(); // remove a tail item
}
}
To draw the snake you just iterate each part drawing it at the X,y position
To test if the snake has run its self over use the following function
function checkForHit(x,y){
for(var i = 0; i < snake.length; i++){
if(snake[i].x === x && snake[i].y === y){
// Snake has hit its self
}
}
}
When the snake eats something it traditionally grows in length. this is easily done by simply increasing the length variable. snakeLength += 1 makes the queue longer.
And a demo as i have not played the game in so long why not.
"use strict";
var score = 0;
var canvas = document.createElement("canvas");
var scoreE = document.createElement("div");
scoreE.style.color = "white";
scoreE.style.font = "16px arial";
scoreE.style.position = "absolute";
scoreE.style.top = "10px";
scoreE.style.left = "10px";
scoreE.style.width = "600px";
scoreE.style.textAlign = "center";
scoreE.textContent = "Click canvas area to get focus";
canvas.width = 600;
canvas.height = 200;
var ctx = this.canvas.getContext("2d");
document.body.appendChild(canvas);
document.body.appendChild(scoreE);
var lastKeyDown = 0;
window.addEventListener('keydown', function(e) {
lastKeyDown = e.keyCode;
e.preventDefault()
})
var snakePartSize = 8;
var playWidth = canvas.width /snakePartSize;
var playHeight = canvas.height /snakePartSize;
var snake = [];
var snakeLength = 10;
var snakePosX = 0;
var snakePosY = 0;
var snakeDirX = 0;
var snakeDirY = 0;
var snakeSpeed = 16; // number of frame between moves
var gameOver = true;
var instDrawn = false;
var food = [];
var foodFreq = 60;
var yum = 0;
var yumCol = ["red","orange","yellow"];
function startSnake(){
ctx.fillStyle = "black";
ctx.fillRect(0,0,canvas.width,canvas.height);
snakePosX = Math.floor(playWidth / 2);
snakePosY = Math.floor(playHeight / 2);
snakeDirX = 0;
snakeDirY = 0;
snakeLength = 10;
snake = [];
snakeSpeed = 16;
move(snakePosX,snakePosY); // set first pos
food = [];
score = 0;
}
function testHit(x,y){
if(x < 0 || y < 0 || y >= playHeight || x >= playWidth ){
return true;
}
for(var i = 0; i < snake.length; i ++){
if(snake[i].x === x && snake[i].y === y){
return true;
}
}
}
function testFood(x,y){
for(var i = 0; i < food.length; i ++){
if(food[i].x === x && food[i].y === y){
food.splice(i,1);
i --;
yum = 4;
score += 100;
snakeLength += 1;
if(snakeLength % 4 === 0){
snakeSpeed -= snakeSpeed > 1 ? 1:0;
}
}
}
}
function addFood(){
var x = Math.floor(Math.random() * playWidth );
var y = Math.floor(Math.random() * playHeight );
if(!testHit(x,y)){
food.push({x:x,y:y});
drawFood();
}
}
function move(x,y){
if(testHit(x,y)){
gameOver = true;
return;
}
testFood(x,y);
snake.push({x : x, y : y});
drawSnakeHead();
if(snake.length > snakeLength){
drawSnakeTail();
snake.shift();
}
}
function drawYum(){
for(var i = 0; i < snake.length; i ++){
ctx.fillStyle = yumCol[yum];
ctx.fillRect(snake[i].x*snakePartSize, snake[i].y*snakePartSize, snakePartSize, snakePartSize);
}
}
function drawFood(){
var f = food[food.length-1];
ctx.fillStyle = "green";
ctx.fillRect(f.x*snakePartSize, f.y*snakePartSize, snakePartSize, snakePartSize);
}
function drawSnakeHead(){
var head = snake[snake.length-1];
ctx.fillStyle = "red";
ctx.fillRect(head.x*snakePartSize, head.y*snakePartSize, snakePartSize, snakePartSize);
}
function drawSnakeTail(){
var head = snake[0];
ctx.fillStyle = "black";
ctx.fillRect(head.x*snakePartSize, head.y*snakePartSize, snakePartSize, snakePartSize);
}
var counter = 0;
function update(){
counter += 1;
if(!gameOver){
if(snakeDirX === 0){
if(lastKeyDown === 37){ // left
snakeDirX = -1;
snakeDirY = 0;
}
if(lastKeyDown === 39){ // right
snakeDirX = 1;
snakeDirY = 0;
}
}
if(snakeDirY === 0){
if(lastKeyDown === 38){ // up
snakeDirY = -1;
snakeDirX = 0;
}
if(lastKeyDown === 40){ // down
snakeDirY = 1;
snakeDirX = 0;
}
}
lastKeyDown = 0;
if(counter % foodFreq ===0){
addFood();
}
if(counter % snakeSpeed === 0){
snakePosX += snakeDirX;
snakePosY += snakeDirY;
score += 1;
move(snakePosX ,snakePosY);
}
if((counter % 2 === 0) && yum > 0){
yum -= 1;
drawYum();
}
scoreE.textContent = "Score : "+ score;
}
if(gameOver){
if(!instDrawn){
instDrawn = true;
ctx.fillStyle = "white";
ctx.font = "32px arial";
ctx.textAlign = "center";
ctx.fillText("GAME OVER",canvas.width /2, canvas.height /2);
ctx.font = "16px arial";
ctx.fillText("Press a direction key to start.",canvas.width /2, canvas.height /2+32);
}
if(lastKeyDown >= 37 && lastKeyDown <= 40){
gameOver = false;
instDrawn = false;
counter = -1;
startSnake();
}
}
requestAnimationFrame(update);
}
requestAnimationFrame(update);
startSnake();

Related

Difficulty Adding a "Play Again!" Button to this snake game

I've been trying to figure out how I can add a play again button to refresh the page after a player has lost. This is a classic snake game. I followed a tutorial on it and but they never said anything about a Play Again button. Any help would be appreciated. Nothing too complicated though please, I'm still learning.
const ctx = canvas.getContext("2d");
class SnakePart {
constructor(x, y) {
this.x = x;
this.y = y;
}
}
let speed = 7;
let tileCount = 20;
let tileSize = canvas.width / tileCount - 2;
let headX = 10;
let headY = 10;
const snakeParts = [];
let tailLength = 2;
let appleX = 5;
let appleY = 5;
let inputsXVelocity = 0;
let inputsYVelocity = 0;
let xVelocity = 0;
let yVelocity = 0;
let score = 0;
const gulpSound = new Audio("gulp.mp3");
//game loop
function drawGame() {
xVelocity = inputsXVelocity;
yVelocity = inputsYVelocity;
changeSnakePosition();
let result = isGameOver();
if (result) {
return;
}
clearScreen();
checkAppleCollision();
drawApple();
drawSnake();
drawScore();
if (score > 5) {
speed = 9;
}
if (score > 10) {
speed = 11;
}
setTimeout(drawGame, 1000 / speed);
}
function isGameOver() {
let gameOver = false;
if (yVelocity === 0 && xVelocity === 0) {
return false;
}
//walls
if (headX < 0) {
gameOver = true;
} else if (headX === tileCount) {
gameOver = true;
} else if (headY < 0) {
gameOver = true;
} else if (headY === tileCount) {
gameOver = true;
}
for (let i = 0; i < snakeParts.length; i++) {
let part = snakeParts[i];
if (part.x === headX && part.y === headY) {
gameOver = true;
break;
}
}
if (gameOver) {
ctx.fillStyle = "white";
ctx.font = "50px Verdana";
if (gameOver) {
ctx.fillStyle = "white";
ctx.font = "50px Verdana";
var gradient = ctx.createLinearGradient(0, 0, canvas.width, 0);
gradient.addColorStop("0", " magenta");
gradient.addColorStop("0.5", "blue");
gradient.addColorStop("1.0", "red");
// Fill with gradient
ctx.fillStyle = gradient;
ctx.fillText("Game Over!", canvas.width / 6.5, canvas.height / 2);
}
ctx.fillText("Game Over!", canvas.width / 6.5, canvas.height / 2);
}
return gameOver;
}
function drawScore() {
ctx.fillStyle = "white";
ctx.font = "10px Verdana";
ctx.fillText("Score " + score, canvas.width - 50, 10);
}
function clearScreen() {
ctx.fillStyle = "black";
ctx.fillRect(0, 0, canvas.width, canvas.height);
}
function drawSnake() {
ctx.fillStyle = "green";
for (let i = 0; i < snakeParts.length; i++) {
let part = snakeParts[i];
ctx.fillRect(part.x * tileCount, part.y * tileCount, tileSize, tileSize);
}
snakeParts.push(new SnakePart(headX, headY)); //put an item at the end of the list next to the head
while (snakeParts.length > tailLength) {
snakeParts.shift(); // remove the furthet item from the snake parts if have more than our tail size.
}
ctx.fillStyle = "orange";
ctx.fillRect(headX * tileCount, headY * tileCount, tileSize, tileSize);
}
function changeSnakePosition() {
headX = headX + xVelocity;
headY = headY + yVelocity;
}
function drawApple() {
ctx.fillStyle = "red";
ctx.fillRect(appleX * tileCount, appleY * tileCount, tileSize, tileSize);
}
function checkAppleCollision() {
if (appleX === headX && appleY == headY) {
appleX = Math.floor(Math.random() * tileCount);
appleY = Math.floor(Math.random() * tileCount);
tailLength++;
score++;
gulpSound.play();
}
}
document.body.addEventListener("keydown", keyDown);
function keyDown(event) {
//up
if (event.keyCode == 38 || event.keyCode == 87) {
//87 is w
if (inputsYVelocity == 1) return;
inputsYVelocity = -1;
inputsXVelocity = 0;
}
//down
if (event.keyCode == 40 || event.keyCode == 83) {
// 83 is s
if (inputsYVelocity == -1) return;
inputsYVelocity = 1;
inputsXVelocity = 0;
}
//left
if (event.keyCode == 37 || event.keyCode == 65) {
// 65 is a
if (inputsXVelocity == 1) return;
inputsYVelocity = 0;
inputsXVelocity = -1;
}
//right
if (event.keyCode == 39 || event.keyCode == 68) {
//68 is d
if (inputsXVelocity == -1) return;
inputsYVelocity = 0;
inputsXVelocity = 1;
}
}
drawGame();```
The easiest way to refresh the page would be just:
window.location.reload(false)
Source:
https://www.freecodecamp.org/news/location-reload-method-how-to-reload-a-page-in-javascript/
I would suggest that simply reloading the page is not a great way to implement a play again feature but I appreciate the creativity of it.

How can i add a Start button to this function?

I'm trying to figure out how I can add a start button to play a javascript game by replacing the audio in the background. I came across this game, the way it works is as soon as you load the page the music plays in the background and the games already started. When I removed the audio link, the game paused after the players 3 lives are up, if I leave the audio in, then when the 3 lives are up you can see your points and a pop up message, can someone please help me understand this
here is a link to the game so you can look at the code and understand what I'm trying to say : https://jsfiddle.net/74nbrdak/embedded/result/
<div>
<canvas id="canvas" width="1000" height="500"></canvas>
</div>
<audio id="background-music" preload="auto" autoplay loop>
<source
src="https://dl.dropbox.com/s/5r3iu7kjsl0mx81/Wildfire%20Cut%20Loopable.wav" type="audio/wav">
function ShowGamesFinished() {
var message = gamesfinished[Math.floor(Math.random() * gamesfinished.length)];
document.getElementById("background-music").pause();
When I removed the audio link, the game paused after the players 3 lives are up, if I leave the audio in, then when the 3 lives are up you can see your points and a pop up message, can someone please help me understand this
So, In the second scenario when the audio element is on the page, the game works just as the creator intended.
In the first scenario when the audio element isn't on the page, the game works fine until the function that handles the game over is called. What causes the problem in that function is this line document.getElementById("background-music").pause();. Since the audio element doesn't exist, it throws an error and the game over screen isn't drawn. Hope that this helps
If you are using pure javascript Without any external libraries, you can initialize your canvas and on a click of the button you can start animating the canvas and your game starts.
let me know If you don't get my answer.
At first glance, removing the audio tag should not have any effect at all on the javascript. The audio plays upon openeing the page because the audio tag has the autoplay attribute.
All of the javascript code seems to be just within a script tag, so it will also autorun once the page gets opened. What you could try is wrapping the entire code from the fiddle into a function and just bind it to your button.
Something like:
<!DOCTYPE html>
<html lang="en">
<head>
<style>
h1 {
font-family: Architects Daughter;
text-align: center;
font-size: 48pt;
margin-top: 50px;
margin-bottom: 0px;
}
h2 {
font-family: Architects Daughter;
text-align: center;
font-size: 28pt;
margin-top: 0px;
margin-bottom: 50px;
}
span {
display: block;
font-family: Arial;
text-align: center;
margin-bottom: 2px;
}
div {
display: flex;
justify-content: space-around;
}
canvas {
border: 2px solid #CC3333;
}
</style>
</head>
<body>
<div>
<canvas id="canvas" width="640" height="360"></canvas>
</div>
<button id="start_game">Start</button>
<script>
var run_game = function() {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var WIDTH = canvas.width;
var HEIGHT = canvas.height;
var updateTime = 20; // Milliseconds
var keys = [false, false, false];
var score = 0;
var kills = 0;
// Player Size = 50x18
var playerHealth = 3;
var playerX = WIDTH / 2;
var playerY = HEIGHT - 20;
var playerSpeed = 6;
var lazerSpeed = 16;
var lazerReloadDistance = playerY - 120;
var lazerLoaded = true;
var lazers = [];
var letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
var maxEnemies = 12;
var enemySpeed = 4;
var enemies = [];
function Clear() {
ctx.fillStyle = "#404040";
ctx.fillRect(0, 0, WIDTH, HEIGHT);
}
function DrawHealth(health) {
ctx.fillStyle = "#E52B50";
ctx.shadowColor = "#E52B50";
ctx.shadowBlur = 15;
ctx.font = "18px Arial";
ctx.textAlign = "start";
var hearts = "";
if (health == 3) {
hearts = "<3 <3 <3";
}
else if (health == 2) {
hearts = "<3 <3 X";
}
else if (health == 1) {
hearts = "<3 X X";
}
else {
hearts = "X X X";
}
ctx.fillText(hearts, 10, 25);
}
function DrawScore() {
ctx.fillStyle = "#FFFF00";
ctx.shadowColor = "#FFFF00";
ctx.shadowBlur = 15;
ctx.font = "18px Arial";
ctx.textAlign = "end";
ctx.fillText(score, WIDTH - 10, 25);
}
function DrawPlayer(x, y) {
ctx.fillStyle = "#1E90FF";
ctx.shadowColor = "#1E90FF";
ctx.shadowBlur = 15;
ctx.font = "24px Arial";
ctx.textAlign = "center";
ctx.fillText("</^\\>", x, y);
}
function Lazer() {
this.x = playerX;
this.y = playerY - 38;
this.draw = function() {
ctx.fillStyle = "#FFFF00";
ctx.shadowColor = "#FFFF00";
ctx.shadowBlur = 15;
this.y -= lazerSpeed;
ctx.fillRect(this.x, this.y, 2, 18);
}
}
function DrawLazers() {
// Check if the last lazer fired is far enough away to fire another
if (lazers.length != 0) {
if (lazers[lazers.length - 1].y <= lazerReloadDistance) {
lazerLoaded = true;
}
}
else {
lazerLoaded = true;
}
for (var i = 0; i < lazers.length; i++) {
var currentLazer = lazers[i];
// Still on screen
if (currentLazer.y > -20) {
currentLazer.draw();
}
else {
lazers.splice(i, 1);
}
}
}
function Enemy(x) {
this.x = x;
this.y = 0;
this.health = Math.ceil(Math.random() * 4);
this.speed = enemySpeed / this.health;
var letterIndex = Math.floor(Math.random() * letters.length);
this.letter = letters.substr(letterIndex, 1);
this.size = 24 + (this.health * 4); // Font size based on health
ctx.font = this.size+"px Arial";
this.width = ctx.measureText(this.letter).width;
this.height = this.size * 0.75; // Approximate height;
this.draw = function() {
ctx.fillStyle = "#FF0040";
ctx.shadowColor = "#FF0040";
ctx.shadowBlur = 15;
ctx.font = this.size+"px Arial";
ctx.textAlign = "center";
this.y += this.speed;
ctx.fillText(this.letter, this.x, this.y);
}
}
function DrawEnemies() {
// Spawn new enemies
if (Math.random() <= 0.05 && enemies.length < maxEnemies) {
var randX = 40 + Math.floor(Math.random() * (WIDTH - 80));
enemies.push(new Enemy(randX));
}
for (var i = 0; i < enemies.length; i++) {
var currentEnemy = enemies[i];
if (currentEnemy.health <= 0) {
enemies.splice(i, 1);
score += 25;
kills++;
continue;
}
// Put enemies that passed the player back at the top
if (currentEnemy.y > HEIGHT + currentEnemy.height) {
currentEnemy.y = 0;
continue;
}
currentEnemy.draw();
}
}
var gameOverMessages = [
"You're in a better place",
"You're Cooked!",
"You gave it your all",
"At least you tried",
"You're Ruined!",
"You're Finished!"
];
function DrawGameOver() {
var message = gameOverMessages[Math.floor(Math.random() * gameOverMessages.length)];
// after deleting the audio element, this doesnt work anymore.
// document.getElementById("background-music").pause();
ctx.fillStyle = "#505050";
ctx.shadowColor = "#505050";
ctx.shadowBlur = 15;
ctx.fillRect(50, (HEIGHT / 2) - 100, WIDTH - 100, 200)
ctx.fillStyle = "#FFFFFF";
ctx.shadowColor = "#FFFFFF";
ctx.shadowBlur = 15;
ctx.textAlign = "center";
ctx.font = "36pt Arial";
ctx.fillText(message, WIDTH / 2, HEIGHT / 2 - 40);
ctx.textAlign = "end";
ctx.font = "18pt Arial";
ctx.fillText("Final Score - ", WIDTH / 2, HEIGHT / 2 + 30);
ctx.textAlign = "start";
ctx.fillStyle = "#FFFF00";
ctx.shadowColor = "#FFFF00";
ctx.fillText(score, WIDTH / 2, HEIGHT / 2 + 30);
ctx.fillStyle = "#FFFFFF";
ctx.shadowColor = "#FFFFFF";
ctx.textAlign = "end";
ctx.font = "18pt Arial";
ctx.fillText("Total Kills - ", WIDTH / 2, HEIGHT / 2 + 60);
ctx.textAlign = "start";
ctx.fillStyle = "#FF0040";
ctx.shadowColor = "#FF0040";
ctx.fillText(kills, WIDTH / 2, HEIGHT / 2 + 60);
}
////////////////////
// Core Functions //
////////////////////
var collidedEnemyIndex = -1;
function CheckCollision() {
for (var i = 0; i < enemies.length; i++) {
var currentEnemy = enemies[i];
// Check if enemy hits player. The 2 is to account for the text width of the player
if (
currentEnemy.x <= playerX - 2 + 25 + (currentEnemy.width / 2) &&
currentEnemy.x >= playerX - 2 - 25 - (currentEnemy.width / 2) &&
currentEnemy.y >= playerY - 18 &&
currentEnemy.y <= playerY + currentEnemy.height &&
collidedEnemyIndex != enemies.indexOf(currentEnemy)
)
{
collidedEnemyIndex = enemies.indexOf(currentEnemy);
playerHealth--;
}
// Reset the index of the enemy colliding with the player
if (collidedEnemyIndex == enemies.indexOf(currentEnemy) && currentEnemy.y < HEIGHT / 2) {
collidedEnemyIndex = -1;
}
for (var j = 0; j < lazers.length; j++) {
var currentLazer = lazers[j];
if (
currentLazer.x <= currentEnemy.x + (currentEnemy.width / 2) &&
currentLazer.x >= currentEnemy.x - (currentEnemy.width / 2) &&
currentLazer.y <= currentEnemy.y
)
{
currentEnemy.health--;
score += 10;
lazers.splice(lazers.indexOf(currentLazer), 1);
}
}
}
}
function HandleInput() {
if (keys[0] == true && keys[1] == false && playerX <= WIDTH - 30) {
playerX += playerSpeed;
}
if (keys[1] == true && keys[0] == false && playerX >= 30) {
playerX -= playerSpeed;
}
if (keys[2]) {
if (lazerLoaded) {
lazers.push(new Lazer());
lazerLoaded = false;
}
}
}
function KeysDown(e) {
e.preventDefault();
// Right
if (e.keyCode == 39) {
keys[0] = true;
}
// Left
else if (e.keyCode == 37) {
keys[1] = true;
}
// Up/Fire
if (e.keyCode == 38) {
keys[2] = true;
}
}
function KeysUp(e) {
// Right
if (e.keyCode == 39) {
keys[0] = false;
}
// Left
else if (e.keyCode == 37) {
keys[1] = false;
}
// Up/Fire
if (e.keyCode == 38) {
keys[2] = false;
}
}
document.addEventListener("keydown", KeysDown, true);
document.addEventListener("keyup", KeysUp, true);
function Update() {
Clear();
HandleInput();
CheckCollision();
DrawEnemies();
DrawLazers();
DrawPlayer(playerX, playerY);
DrawHealth(playerHealth);
DrawScore();
if (playerHealth <= 0) {
clearInterval(gameLoop);
DrawGameOver();
}
}
var gameLoop = setInterval(Update, updateTime);
};
document.querySelector( '#start_game' ).addEventListener( 'click', run_game );
</script>
</body>
</html>

Why is this text disappearing but not the shape?

How do I make the shape disappear like the text does? I've gone through the code and they're practically identical except that one is created when the user spins the mouse wheel and the other is created when the user clicks on the screen, but the text disappears after time and the triangle does not. I feel like there's something small I must be missing. Here's the code:
<html>
<head>
<script>
var canvas;
var context;
var triangles = [];
var texts = [];
var timer;
var textSayings = ['Cool!', 'Nice!', 'Awesome!', 'Wow!', 'Whoa!', 'Super!', 'Woohoo!', 'Yay!', 'Yeah!', ':)', ':D'];
function init() {
canvas = document.getElementById('canvas');
context = canvas.getContext("2d");
//resize canvas to fit the window
resizeCanvas();
window.addEventListener('resize', resizeCanvas, false);
window.addEventListener('orientationchange', resizeCanvas, false);
canvas.onwheel = function(event) {
handleWheel(event.clientX, event.clientY);
};
canvas.onclick = function(event) {
handleClick(event.clientX, event.clientY);
}
var timer = setInterval(resizeCanvas, 30);
}
function Triangle(x,y,triangleColor) {
this.x = x;
this.y = y;
this.triangleColor = triangleColor;
this.vx = Math.random() * 80 - 40;
this.vy = Math.random() * 80 - 40;
this.time = 250;
}
function Text(x,y,textColor,word) {
this.x = x;
this.y = y;
this.word = word;
this.textColor = textColor;
this.vx = Math.random() * 20 - 10;
this.vy = Math.random() * 20 - 10;
this.time = 300;
}
function handleWheel(x,y) {
var colors = [[255,0,0],[255,255,255],[0,0,255]];
var triangleColor = colors[Math.floor(Math.random()*colors.length)];
triangles.push(new Triangle(x,y,triangleColor));
for (var i=0; i<triangles.length; i++) {
drawTriangle(triangles[i]);
}
}
function handleClick(x,y) {
var colors = [[255,0,0],[255,255,0],[0,0,255]];
var textColor = colors[Math.floor(Math.random()*colors.length)];
texts.push(new Text(x,y,textColor,pickWord()));
for (var i=0; i<texts.length; i++) {
drawText(texts[i]);
}
}
function timeToFade(time) {
if(time > 100) {
return 1;
}
else {
return time / 100;
}
}
function pickWord() {
return textSayings[Math.floor(Math.random() * textSayings.length)];
}
function drawText(text) {
context.font = "bold 80px Verdana";
var gradient=context.createLinearGradient(0,0,canvas.width,0);
gradient.addColorStop("0","magenta");
gradient.addColorStop("0.25","yellow");
gradient.addColorStop("0.5","lime");
gradient.addColorStop("0.75","aqua");
gradient.addColorStop("1.0","magenta");
context.fillStyle = gradient;
context.fillText(text.word,text.x,text.y);
}
function drawTriangle(triangle) {
context.beginPath();
context.moveTo(triangle.x,triangle.y);
context.lineTo(triangle.x+25,triangle.y+25);
context.lineTo(triangle.x+25,triangle.y-25);
var gradient = context.createLinearGradient(0,0,canvas.width,0);
gradient.addColorStop("0","red");
gradient.addColorStop("0.25","salmon");
gradient.addColorStop("0.5","aqua");
gradient.addColorStop("0.75","lime");
gradient.addColorStop("1.0","orange");
context.fillStyle = gradient;
context.fill();
}
function resizeCanvas() {
canvas.width = window.innerWidth-20;
canvas.height = window.innerHeight-20;
fillBackgroundColor();
for (var i=0; i<triangles.length; i++) {
var t = triangles[i];
drawTriangle(t);
if (t.x + t.vx > canvas.width || t.x + t.vx < 0)
t.vx = -t.vx
if (t.y + t.vy > canvas.height || t.y + t.vy < 0)
t.vy = -t.vy
if (t.time === 0) {
triangles.splice(i,1);
}
t.time -= 3;
t.x += t.vx;
t.y += t.vy;
}
for (var i=0; i<texts.length; i++) {
var te = texts[i];
drawText(te);
if (te.x + te.vx > canvas.width || te.x + te.vx < 0)
te.vx = -te.vx
if (te.y + te.vy > canvas.height || te.y + te.vy < 0)
te.vy = -te.vy
if (te.time === 0) {
texts.splice(i,1);
}
te.time -= 3;
te.x += te.vx;
te.y += te.vy;
}
}
function fillBackgroundColor() {
context.globalCompositeOperation = 'source-over';
context.fillStyle = 'rgba(0, 0, 0, 1)';
context.fillRect(0,0,canvas.width,canvas.height);
context.globalCompositeOperation = 'lighter';
}
window.onload = init;
</script>
</head>
<body>
<canvas id="canvas" width="500" height="500"></canvas>
</body>
</html>
It's because the triangle time isn't a multiple of 3, while the text time is so when you check this if statement:
if (t.time === 0) {
triangles.splice(i,1);
}
It's never true.
You can fix this by changing the if statement to:
if (t.time <= 0) {
triangles.splice(i,1);
}
This is actually my fault since it's a bug that was in my previous answer. Sorry about that.
jsfiddle:
https://jsfiddle.net/0rst8def/

Objects in P5 do not collide when using collide() function

I'm working on getting all the components for my final together using the P5.play engine and while I have made some progress with setting up aspects of my mini game I'm having a hard time with the collision. It should be easy but for whatever reason when I set up my two objects (the fish and the garbage) they do not collide. I am trying to set it up so that when the garbage collides with the fish the fish either get removed or are reset to a place where they can continue to move on the screen while tallying the score. I managed to get the player sprite to collect the garbage and add to the score using overlapPoint and placing the condition in the update for the garbage object. But when I attempt the same technique for the fish on the garbage object an error occurs and everything disappears on the screen. I commented out the portion that is I have tried multiple ways including the collide() function on the objects with the proper conditionals but nothing seems to work. A bit frustrating. I have tried various other ways. So I'm asking for expert advice. Any assistance is appreciated. this is the code that i have thus far:
var bg;
var player;
var player_stand_sprites;
var player_stand;
var fish_swim_sprites;
var fish_swim;
var fish = [];
var garbage_drop_sprites;
var garbage_drop;
var garbage = [];
var score = 0;
function preload() {
bg = loadImage("final-bg.png");
player_stand_sprites = loadSpriteSheet("player2.png", 100, 100, 1);
player_stand = loadAnimation(player_stand_sprites);
fish_swim_sprites = loadSpriteSheet("fish.png", 75, 75, 1);
fish_swim = loadAnimation(fish_swim_sprites);
garbage_drop_sprites = loadSpriteSheet("metal.png", 41, 75, 1);
garbage_drop = loadAnimation(garbage_drop_sprites);
}
function setup() {
createCanvas(720, 360);
player = createSprite(100, 0);
player.addAnimation("stand", player_stand);
player.setCollider("circle", 0, 0, 32, 32);
player.depth = 10;
//player.debug = true;
//to make fish
for (var i = 0; i < 10; i++){
fish.push( new Fish(random(0,width), random(height/2, height)) );
for (var i = 0; i < fish.length; i++) {
fish[i].init();
}
}
//to make garbage
for (var a = 0; a < 5; a++){
garbage.push( new Garbage(random(0,width), random(width/2, width)));
}
}
function draw() {
background(bg);
player.position.x = mouseX;
player.position.y = mouseY;
for (var i = 0; i < fish.length; i++) {
fish[i].update();
}
for (var a = 0; a < garbage.length; a++) {
garbage[a].update();
}
/**for (var b = 0; b < fish.length; b++) {
if(fish[b].collide(garbage[b])){
fish[b].remove;
}
}**/
text(score,100,100);
drawSprites();
}
function Garbage(x,y){
this.sprite = createSprite(x, y);
this.sprite.addAnimation("drop", garbage_drop);
this.sprite.setCollider("circle",0,0,32,32);
this.speed = random(1,2);
this.sprite.debug = true;
this.update = function() {
this.sprite.position.y += this.speed;
if(this.sprite.position.y > height){
this.sprite.position.y = 0;
}
if(this.sprite.overlapPoint(player.position.x, player.position.y)){
this.sprite.position.x = random(0,width);
this.sprite.position.y = -75;
score++;
}
}
}
function Fish(x,y) {
this.sprite = createSprite(x, y);
this.sprite.addAnimation("swim", fish_swim);
this.sprite.setCollider("rectangle",0,0,75,32);
this.speed = 0;
this.sprite.debug = true;
this.init = function() {
if (this.sprite.position.x < width/2) {
this.sprite.mirrorX(-1);
this.speed = random(1, 2);
} else {
this.speed = -random(1,2);
}
}
this.update = function() {
this.sprite.position.x += this.speed;
if(this.sprite.position.x > width){
this.sprite.position.x = 0;
}else if(this.sprite.position.x < -width){
this.sprite.position.x = width;
}
}
}
I actually found the answer to my question a while back but am going to post it here.
The initial problem was that the sprites would not collide but with a simple for loop nested within another for loop and adding a .sprite to each of the objects being checked, I was able to get all the elements to collide properly.
Here is the code I revised to make it work seamlessly using the P5.play.js library:
var bg;
var img;
var dead = false;
var deadFish = 0;
var player;
var player_stand_sprites;
var player_stand;
var fish_swim_sprites;
var fish_swim;
var fish = [];
var garbage_drop_sprites;
var garbage_drop;
var garbage = [];
var score = 0;
//////////////////////////////////////////
function preload() {
bg = loadImage("final-bg.png");
img = loadImage("fish.png");
player_stand_sprites = loadSpriteSheet("player2.png", 100, 100, 1);
player_stand = loadAnimation(player_stand_sprites);
fish_swim_sprites = loadSpriteSheet("fish.png", 75, 75, 1);
fish_swim = loadAnimation(fish_swim_sprites);
garbage_drop_sprites = loadSpriteSheet("metal.png", 41, 75, 1);
garbage_drop = loadAnimation(garbage_drop_sprites);
}
//////////////////////////////////////////
function setup() {
createCanvas(720, 360);
player = createSprite(100, 0);
player.addAnimation("stand", player_stand);
player.setCollider("circle", 0, 0, 32, 32);
player.depth = 10;
//player.debug = true;
//to make fish
for (var i = 0; i < 10; i++){
fish.push( new Fish(random(0,width), random(height/2, height)) );
for (var i = 0; i < fish.length; i++) {
fish[i].init();
}
}
//to make garbage
for (var a = 0; a < 5; a++){
garbage.push( new Garbage(random(0,width), random(width/2, width)));
}
}
function draw() {
scene_start();
}
//////////////////////////////////////////
function scene_start(){
push();
background("green");
fill("white");
textAlign(CENTER);
textSize(50);
textStyle(BOLD);
text("SPOT A FISH", width/2,height/3.5);
image(img, width/2.3, height/3);
textSize(15);
text("Rules: dont let the cans touch the fish. 5 fish die and you must start over", width/2, height/1.5);
textSize(30);
text("press up arrow key to start", width/2, height/1.2);
pop();
if (keyCode == UP_ARROW) {
scene_1();
}
}
function scene_1(){
background(bg);
score_card();
if(!dead){
player.position.x = mouseX;
player.position.y = mouseY;
for (var i = 0; i < fish.length; i++) {
fish[i].update();
}
for (var i = 0; i < garbage.length; i++) {
garbage[i].update();
}
for (var a = 0; a < garbage.length; a++) {
for (var b = 0; b < fish.length; b++) {
if(fish[b].sprite.collide(garbage[a].sprite)){
fish[b].sprite.position.x = random(-500, -100);
deadFish ++;
if(deadFish === 5){
dead = true;
}
}
}
}
drawSprites();
}else{
score_card();
textSize(30);
textStyle(BOLD);
textAlign(CENTER);
text("YOU DIED PLEASE TRY AGAIN",width/2,height/2);
text("press any button to start again",width/2,height/1.5);
if(keyIsPressed === true){
deadFish = 0;
dead = false;
}
}
}
function Garbage(x,y){
this.sprite = createSprite(x, y);
this.sprite.addAnimation("drop", garbage_drop);
this.sprite.setCollider("circle",0,0,32,32);
this.speed = random(1,2);
//this.sprite.debug = true;
this.update = function() {
this.sprite.position.y += this.speed;
if(this.sprite.position.y > height){
this.sprite.position.y = 0;
}
if(this.sprite.overlapPoint(player.position.x, player.position.y)){
this.sprite.position.x = random(0,width);
this.sprite.position.y = random(-200,-75);
score++;
}
if(score === 100){
this.speed = random(2,3);
score += 1000;
}else if(score === 1200){
this.speed = random(3,3.5);
score += 1000;
}
}
}
var score_card = function(){
fill("black");
rect(0,0,width,30);
textStyle(BOLD);
fill("white");
text("SCORE: "+score,10,20);
text("DEAD FISH: "+deadFish,width/1.2,20)
}
function Fish(x,y) {
this.sprite = createSprite(x, y);
this.sprite.addAnimation("swim", fish_swim);
this.sprite.setCollider("rectangle",0,0,75,32);
this.speed = 0;
this.sprite.debug = true;
this.init = function() {
if (this.sprite.position.x < width/2) {
this.sprite.mirrorX(-1);
this.speed = random(1, 2);
} else {
this.speed = -random(1,2);
}
}
this.update = function() {
this.sprite.position.x += this.speed;
if(this.sprite.position.x > width){
this.sprite.position.x = 0;
}else if(this.sprite.position.x < -width){
this.sprite.position.x = width;
}
}
}

Snake eating food (HTML5 canvas game)

This is my first post so I hope that I put everything correctly down below here! :-P
I have a problem. Currently I'm making a snake game with a school friend of mine. We are making a snake game by using node.js so we can create a multiplayer snake game. Nothing really extreme just the basic snake game but then with more players.
Currently I've created a code that can move the snake and also will place food randomly on the canvas (I'm using the HTML5 Canvas element in which the game is played).
Now I'm stuck because I want to create a function that allows the snake to eat the food and then grow longer. As far as I know I have the function as it should be, but for some reason it does not work. My knowledge of javascript is very basic so what I'm doing here is all new for me. I will put the entire code down below so you can see it through.
I've created 2 javascript files. one that has the snake code in it and the other has the food code in it. The function that I'm referring about is inside the Snake script under Snake.prototype.move
I really hope that someone can help me out so I can proceed with our game.
This is the main code (Snake code):
var game;
$(document).ready(function(){
var canvas = $("#canvas")[0];
var ctx = canvas.getContext("2d");
var w = $("#canvas").width();
var h = $("#canvas").height();
var cw = 10;
ctx.fillStyle = "white";
ctx.fillRect(0, 0, w, h);
ctx.strokeStyle = "black";
ctx.strokeRect(0, 0, w, h);
var GameObject = function() {
this.snakes = [];
this.foods = [];
}
game = new GameObject();
var snake = new Snake(1, 15, 'testnaam');
snake.create();
game.snakes.push(snake);
game.foods.push(new Food(w, cw));
function loop() {
window.setTimeout(loop, 60);
ctx.clearRect(0, 0, w, h);
if(game.snakes.lenght !== 0) {
for(i = 0; i < game.snakes.length; i++) {
var s = game.snakes[i];
s.paint(ctx, game);
}
} else {
}
if(game.foods.length !== 0) {
for(var i = 0; i < game.foods.length; i++) {
var f = game.foods[i];
f.paint(ctx);
}
} else {
}
}
loop();
document.addEventListener('keydown', function(e) {
e.preventDefault();
var key = e.which;
if(key == "37" && snake.direction !="right") snake.direction = "left";
else if(key == "38" && snake.direction !="down") snake.direction = "up";
else if(key == "39" && snake.direction !="left") snake.direction = "right";
else if(key == "40" && snake.direction !="up") snake.direction = "down";
}, false);
});
var Snake = function(player, length, alias){
this.length = length;
this.pieces = [];
this.player = player;
this.position = {x: 0, y: 0};
this.direction = "right";
this.color = this.color();
this.getName = alias;
}
Snake.prototype.create = function(){
for(var i = this.length -1; i >= 0; i--) {
this.pieces.push({x: i, y: 0});
}
};
Snake.prototype.paint = function(ctx, game){
this.move(game);
for(var i = 0; i < this.pieces.length; i++){
var c = this.pieces[i];
ctx.fillStyle = this.color;
ctx.fillRect(c.x*10, c.y*10, 10, 10);
}
};
Snake.prototype.color = function(){
var letters = '0123456789ABCDEF'.split('');
var color = '#';
for (var i = 0; i < 6; i++ ) {
color += letters[Math.round(Math.random() * 15)];
}
return color;
};
Snake.prototype.getName = function() {
return this.alias;
}
Snake.prototype.getPosition = function() {
return {x: this.x, y: this.y }
}
Snake.prototype.move = function(game) {
var nx = this.pieces[0].x;
var ny = this.pieces[0].y;
if(this.direction == "right")nx++;
else if(this.direction == "left")nx--;
else if(this.direction == "up")ny--;
else if(this.direction == "down")ny++;
if(Snake == game.foods[0].position.x && Snake == game.foods[0].position.y){
console.log("raak");
var tail = {
x: nx,
y: ny
};
Food.create();
} else{
var tail = this.pieces.pop();
tail.x = nx;
tail.y = ny;
}
this.pieces.unshift(tail);
};
Snake.prototype.collision = function(x, y, array){
for(var i = 0; i < array.length; i++){
if(array[i].x == x && array[i].y == y)
return true;
}
return false;
};
And This is the code for the food
var Food = function(w, cw){
this.w = w;
this.cw = cw;
this.position = this.create();
console.log(this.position);
};
Food.prototype.create = function(){
var min = 0;
var max = (this.w/this.cw);
return position = {
x: Math.round(min + Math.random()* (Math.abs(min)+(max)))*this.cw,
y: Math.round(min + Math.random()* (Math.abs(min)+(max)))*this.cw
}
};
Food.prototype.paint = function(ctx){
ctx.fillStyle = "#000";
ctx.fillRect(this.position.x,this.position.y,10,10)
};
Thank you very much!
Live demo
I had to fiddle with it a lot.. there is a lot of weirdness going on in the code, but this is the area I messed with primarily to get it working.
Snake.prototype.move = function (game) {
var nx = this.pieces[0].x;
var ny = this.pieces[0].y;
if (this.direction == "right") nx++;
else if (this.direction == "left") nx--;
else if (this.direction == "up") ny--;
else if (this.direction == "down") ny++;
/*
* you werent testing the front pieces x and y, also since your multiplying the snake
* pieces by 10, you need to divide the food positions by 10 for the coords to match up
*/
if (this.pieces[0].x == game.foods[0].position.x / 10 && this.pieces[0].y == game.foods[0].position.y / 10) {
console.log("raak");
var tail = {
x: nx,
y: ny
};
// push your piece
this.pieces.push(tail);
// you have an array for prob to eventually have more than one on the screen.
// for now i set food[0] to be a new piece of food. We dont have ref's to w and cw in this
// func to I passed in the values.
game.foods[0] = new Food(canvas.width, 10);
} else {
var tail = this.pieces.pop();
tail.x = nx;
tail.y = ny;
// only unshift when we havent added a piece
this.pieces.unshift(tail);
}
};
Basically you weren't testing the positions at all and you werent dividing the foods position by 10 when checking so the snake's position could never match the foods.

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